There are hundreds of different muscles in the human body, and a plethora of other connective tissues and anatomical structures for which exercise and stretching may improve strength and/or mobility. Different stretches or exercises may benefit different subsets of these muscles and connective tissues, with tens of thousands of combinations being possible. Moreover, human fitness can be defined or measured in various ways, many of which are personal and subjective to the exercise apparatus user. Hence, subtle differences in an exercise apparatus may unpredictably change the commercial or practical success of the apparatus.
Many contemporary exercise machines focus on muscle groups that are already well developed in the average user. Other contemporary exercise machines may focus on often under-developed muscle groups, but may invite injury by presenting too much or too little resistance to motion, and/or too easily allow over-stretching of muscles or connective tissue. Other contemporary exercise machines may avoid one or more of the foregoing pitfalls, but at a cost or with complexity that inhibits market acceptance.
Hence there is an ongoing substantial need in the art for improved exercise apparatus designs that can safely improve strength and/or flexibility of connective tissue and muscle combinations that are often under-developed in the average human, with adequate service life and reliability, and that can be practically manufactured at a cost that allows marketability at a profit.